The present invention relates to an adjustable wheel and axle assembly for a work vehicle such as an agricultural tractor and in particular to a wheel and axle assembly that enables the wheel position to be infinitely adjusted along the length of the axle.
Adjustable wheel and axle assemblies are known as shown in FIG. 1. The assembly of FIG. 1 is disclosed in U.S. Pat. No. 4,936,634. There an axle shaft 12 carries the adjustable wheel assembly 14. The wheel assembly 14 includes an outer wheel hub 18 having a tapered bore 24 large enough to accommodate the axle shaft 12 and provide an annular tapered bore in which upper and lower tapered flanged sleeves 26 and 28, respectively, can be received in a wedging action within the tapered bore 24. The upper tapered flanged sleeve 26 has a radially extending, semi-circular flange 30 and a semi-conical, axially extending portion 32. The lower tapered flanged sleeve 28 is of the same configuration as the upper sleeve 26, having a radially extending, semi-circular flange 34 and a semi-conical, axially extending portion 36.
The wheel hub is provided with a plurality of angularly spaced threaded bolt holes 46 that receive a matching quantity of bolts 48a, 48b, 48c and 48d. The semicircular flanges 30, 34 are provided with a plurality of similar angularly spaced bolt holes 50, that align with the threaded bolt holes 46 contained in the wheel hub 22. Also provided in the flanges 30, 34 are additional threaded bolt holes 52 spaced radially the same as the holes 50, but in a different angular relationship to the holes 50. When the bolts 48a-d are threaded into the holes 46 in the wheel hub, the conical portions 32, 36 of the tapered flanged sleeves 26, 28 are drawn tightly into the tapered bore 24 where the sleeves tightly engage the axle 12 to mount the wheel hub 18 to the axle 12.
The taper angle of the bore 24 and conical portions 32, 36 is not enough to be self releasing. In order to withdraw the conical portion 32, 36 from the bore 24, it is necessary to loosen the bolts 48. Bolts 48b and 48c are removed completely from the bores 50 and are threaded into the bores 52 until they abut against the face 56 of the wheel hub 18. With the aid of an additional torque producing tool, the bolts 48b and 48c are sequentially tightened, thus forcing the upper and lower sleeves 26, 28 to separate from the tapered bore 24. The total clamping force available to mount the wheel and axle assembly is limited by the number of bolts 48 used to draw the sleeves into the bore 24. As the power output of agricultural tractors increases, the wheel clamp load on the axle must also increase to avoid slippage between the axle and the wheel hub.
The present invention provides an improved adjustable wheel and axle assembly that produces a greater clamping force on the axle. This is accomplished by providing the tapered surfaces with a larger taper angle such that the parts are self releasing. This eliminates the need for the separate threaded bores 52 shown in FIG. 1 in the flanges 30, 34. Without the threaded bores 52, space is available in the flanges and hub for additional bolt bores to draw the tapered portions into engagement, thus enabling the clamp load on the axle to be increased.
The adjustable wheel and axle assembly of the present invention has an inner element with a radially outer, double tapered portion having a large center portion and axially inner and outer tapered portions extending axially inward and axially outward from the center portion. The wheel hub has a two-tiered tapered interior bore with a small diameter first tapered portion and a large diameter second tapered portion. The first tapered portion complements and fits onto one of the tapered portions of the inner element while the large diameter second tapered portion is spaced radially outward from the other tapered portion of the inner element. A split ring wedge having radially inner and outer tapered portions fits between the inner element and the large diameter tapered portion of the wheel hub. A plurality of bolts extending through the wheel hub and into the split ring wedge draw the split ring wedge into the wheel hub whereby the inner element is clamped onto the axle. The taper angle is in the range of 14-16 degrees such that the parts are self releasing. This eliminates the need for additional threaded bolt bores in the wheel hub for separating the components and allows for more bolts for generating the clamping force. In addition, the large taper angle enables the axial thickness of the adjustable wheel and axle assembly to be reduced as compared to the assembly shown in FIG. 1.